How to generates leads through SEO?

You need to do a competitive analysis and improve your content, design, links (inbound and outbound) to rank in top 10 or 20. You will see the results time to time as you keep posting interesting topics.

Here are five steps to use SEO to improve your lead generation strategies:
Make a list of relevant keywords
Google them
Organize the results along your sales funnel
Optimize existing content
Create content to fill in the gaps